To make a proper blood vessel, several major cellular processes must be regulated and integrated. Specifically, endothelial cell division occurs in the context of morphogenetic processes that lead to sprout formation, fusion, and expansion of the vascular network. Normally these distinct processes are elegantly interwoven to produce the appropriate amount of vasculature with the proper 3-dimensional pattern. However, relatively little is known about how endothelial cell division and morphogenesis are regulated in space and time during angiogenesis, and even less is known about how these processes integrate to form blood vessels. We have evidence that two major aspects of endothelial cell division are regulated by morphogenetic cues, the rate of cell division and the orientation of the cleavage plane during mitosis. Thus we hypothesize that morphogenetic signals impact specific parameters of endothelial cell division, and that this input is critical to proper vessel morphogenesis. We also hypothesize that morphogenetic signals affecting the rate and orientation of endothelial cell division are transduced via endothelial cell-cell junctions and mitotic polarity components. To test these hypotheses, we will use dynamic imaging to elucidate the "rules" by which endothelial cell division is regulated in time and space during angiogenesis. We will manipulate endothelial junctions and polarity molecules that affect spindle dynamics, and determine the impact of these manipulations on cell division and polarity. Finally, we will examine in detail the role of two signaling pathways, VEGF and Planar Cell Polarity (PCP or non-canonical Wnt signaling) in the co- ordination between endothelial morphogenesis and cell division. A molecular understanding of how cellular processes are integrated during angiogenesis will help in the design of approaches to vessel regeneration. The ability to recapitulate biological processes leading to proper vessel formation is a requirement for many aspects of regenerative medicine, so this work will have high impact in this translational arena. This proposal will use mouse models to examine how the propagation of cells making up the wall of blood vessels affects the form and shape of the vessel. The results will help us understand how vessels are shaped, which in turn will aid in designing ways to make artificial vessels for therapeutic use.